The objective of this project is to develop quantitative estrogen (ER) and progesterone receptor (PgR) measurements using high resolution digital image microscopy combined with immunohistochemistry techniques. These techniques will enable direct measurements of receptor amounts in tissues and cells. The use of image analysis for quantitation of estrogen and progesterone receptors in the clinical pathology laboratory is rapidly becoming an established test. Commercially available image analysis assays only give the percentage of cells that express the receptors, without taking into account the amount of receptors in the cells; thus, are incapable of giving quantitative amounts of steroid receptors. The assay proposed will 1) produce cell pellets with known amounts of steroid receptors (or progesterone receptors) 2) calibrate the imaging system to report estrogen receptor levels (or progesterone receptor levels) using the cell pellets on which the amount of receptors have been pre- determined, and 3) measure the concentration of receptors in tissues, and report the amount of receptors on breast cancer tissue in fmol/mg equivalents of protein. PROPOSED COMMERCIAL APPLICATION: Develop calibration materials and methods to measure estrogen and progesterone receptors from breast cancer patients, to be used in clinical laboratories which use immunohistochemistry and image analysis techniques.